1. Field of the Invention
The invention relates to an injection molding technique for injecting a resin material into a cavity to form an injection molded product. More particularly, the invention relates to a technique that pressurizes a die so as to restrain generation of burr in the molded product formed through the injection molding method.
2. Description of Related Art
A generally employed injection molding apparatus is provided with a clamp mechanism including a hydraulic stuffer or a toggle mechanism for the purpose of maintaining the resin pressure within the cavity constant and restraining deformation of the die. The clamp mechanism serves to clamp a fixed mold and a moveable mold.
There is a known mechanism disclosed in Japanese Patent Publication No. JP-B-6-67582, which pressurizes a die in the direction perpendicular to a die clamping direction in conjunction with a die clamp mechanism so as to restrain deformation of the die caused under the resin pressure without requiring enhancement of rigidity of the die and forming a molded product with high accuracy through an injection molding method at a low cost.
There is also a known apparatus disclosed in Japanese Patent Publication No. JP-B-6-28886, which employs a hydraulic cylinder as the mechanism that pressurizes a die in the direction perpendicular to a die clamping direction.
The generally employed mechanism that pressurizes the die in the direction perpendicular to the die clamping direction requires a pressing unit to be provided for the injection molding apparatus, resulting in increase in both the cost and the system size. The aforementioned mechanism fails to completely prevent generation of burr in the injection molded product.
The technique disclosed in Japanese Patent Publication No. JP-B-6-67582 cannot be realized by a simple structure, and it is difficult to control the pressing force applied to the die in the direction perpendicular to the die clamping direction in accordance with the resin pressure.
The technique disclosed in Japanese Patent Publication No. JP-B-6-28886 may increase the size of the system and elongate the time required for the molding method. Accordingly the control of the injection molding apparatus becomes complicated.